You are having a yard sale. You have a riding lawn mower for sale. A customer is taking it for a test drive, to make sure it starts and it runs and it steers correctly.   While he is driving around, someone else comes up and asks how much you want for the riding lawn mower. You give him a price and he says he'll take it.   Now the first man comes back and stops the mower and says I'll take it.   Who would you sell it to?   My next door neighbor was telling